This is a package for syntax highlighting a large number of different languages. To see the list of
languages currently supported, see the syntax_files directory.
Highlight allows you to pass in a string and get back all the information you need to syntax highlight that string well.
This project is still a work in progress and more features and documentation will be coming later.
go get github.com/zyedidia/highlight
Here is how to use this package to highlight a string. We will also be using github.com/fatih/color to actually
colorize the output to the console.
package main
import (
"fmt"
"io/ioutil"
"strings"
"github.com/fatih/color"
"github.com/zyedidia/highlight"
)
func main() {
// Here is the go code we will highlight
inputString := `package main
import "fmt"
// A hello world program
func main() {
fmt.Println("Hello world")
}`
// Load the go syntax file
// Make sure that the syntax_files directory is in the current directory
syntaxFile, _ := ioutil.ReadFile("highlight/syntax_files/go.yaml")
// Parse it into a `*highlight.Def`
syntaxDef, err := highlight.ParseDef(syntaxFile)
if err != nil {
fmt.Println(err)
return
}
// Make a new highlighter from the definition
h := highlight.NewHighlighter(syntaxDef)
// Highlight the string
// Matches is an array of maps which point to groups
// matches[lineNum][colNum] will give you the change in group at that line and column number
// Note that there is only a group at a line and column number if the syntax highlighting changed at that position
matches := h.HighlightString(inputString)
// We split the string into a bunch of lines
// Now we will print the string
lines := strings.Split(inputString, "\n")
for lineN, l := range lines {
for colN, c := range l {
// Check if the group changed at the current position
if group, ok := matches[lineN][colN]; ok {
// Check the group name and set the color accordingly (the colors chosen are arbitrary)
if group == highlight.Groups["statement"] {
color.Set(color.FgGreen)
} else if group == highlight.Groups["preproc"] {
color.Set(color.FgHiRed)
} else if group == highlight.Groups["special"] {
color.Set(color.FgBlue)
} else if group == highlight.Groups["constant.string"] {
color.Set(color.FgCyan)
} else if group == highlight.Groups["constant.specialChar"] {
color.Set(color.FgHiMagenta)
} else if group == highlight.Groups["type"] {
color.Set(color.FgYellow)
} else if group == highlight.Groups["constant.number"] {
color.Set(color.FgCyan)
} else if group == highlight.Groups["comment"] {
color.Set(color.FgHiGreen)
} else {
color.Unset()
}
}
// Print the character
fmt.Print(string(c))
}
// This is at a newline, but highlighting might have been turned off at the very end of the line so we should check that.
if group, ok := matches[lineN][len(l)]; ok {
if group == highlight.Groups["default"] || group == highlight.Groups[""] {
color.Unset()
}
}
fmt.Print("\n")
}
}If you would like to automatically detect the filetype of a file based on the filename, and have the appropriate definition returned,
you can use the DetectFiletype function:
// Name of the file
filename := ...
// The first line of the file (needed to check the filetype by header: e.g. `#!/bin/bash` means shell)
firstLine := ...
// Parse all the syntax files in an array with type []*highlight.Def
var defs []*highlight.Def
...
def := highlight.DetectFiletype(defs, filename, firstLine)
fmt.Println("Filetype is", def.FileType)For a full example, see the syncat example which acts like cat but will syntax highlight the output (if highlight recognizes the filetype).
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